Question: Although it’s an exceedingly rare occurrence, what happens if East manages to have a winning hand after the Charleston, and the hand was bet on?

Answer: In the highly unlikely event that East has a winning hand after the Charleston, it is considered a self-picked hand, and its value is doubled.  This is also known as an “Earthly Hand.” If the fifth player placed a bet on East, they would be paid out just like the winner.  See also ID94.

Source:   Mah Jongg Made Easy 2024, page 25, #8